wave-image.cpp

Go to the documentation of this file.

/*
 * wave-image.cpp
 *
 * Copyright (C) 2009  Thomas A. Vaughan
 * All rights reserved.
 *
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THOMAS A. VAUGHAN ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THOMAS A. VAUGHAN BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *
 * Basic image loading.  See wave-image.h
 */

// includes --------------------------------------------------------------------
#include "wave-image.h"                 // always include our own header first!

#include "common/wave_ex.h"
#include "nstream/nstream.h"
#include "perf/perf.h"
#include "threadsafe/smart_ptr.h"
#include "wave-jpeg/wave-jpeg.h"
#include "wave-png/wave-png.h"


namespace media {


////////////////////////////////////////////////////////////////////////////////
//
//      static helper methods
//
////////////////////////////////////////////////////////////////////////////////


////////////////////////////////////////////////////////////////////////////////
//
//      Registry -- class that manages all registered image loaders
//
////////////////////////////////////////////////////////////////////////////////

class Registry {
public:
        // public class methods ------------------------------------------------
        void addLoader(IN smart_ptr<ImageLoader>& loader);
        bool load(IN nstream::Manager * mgr, IN const char * name,
                        OUT image_t& image);

private:
        // private typedefs ----------------------------------------------------
        typedef std::vector<smart_ptr<ImageLoader> > vec_loader_t;

        // private member data -------------------------------------------------
        vec_loader_t            m_loaders;
};



void
Registry::addLoader
(
IN smart_ptr<ImageLoader>& loader
)
{
        ASSERT(loader, "null");

        m_loaders.push_back(loader);
}



bool
Registry::load
(
IN nstream::Manager * mgr,
IN const char * name,
OUT image_t& image
)
{
        ASSERT(mgr, "null");
        ASSERT(name, "null");

        DPRINTF("Looking for a loader for image: %s", name);

        // loop through loaders and see if any recognize this
        for (vec_loader_t::iterator i = m_loaders.begin(); i != m_loaders.end();
             ++i) {
                ImageLoader * loader = *i;
                ASSERT(loader, "null");

                DPRINTF("Checking loader '%s'...", loader->getLoaderName());

                if (loader->canLoadImage(mgr, name)) {
                        DPRINTF("Found loader! '%s'", loader->getLoaderName());

                        // great, get a stream!
                        smart_ptr<nstream::File> file = mgr->getEntry(name);
                        ASSERT_THROW(file,
                            "image path is not a file: " << name);
                        smart_ptr<nstream::Stream> stream = file->openStream();
                        ASSERT_THROW(stream,
                            "could not open image file: " << name);

                        // have loader load the image from the stream
                        image.clear();

                        // construct the timer name
                        std::string timerName = "loadImage:";
                        timerName += loader->getLoaderName();
                        {
                                perf::Timer timer(timerName.c_str());
                                loader->load(stream, image);
                        }
                        //image.dump("Just loaded this...");
                        ASSERT_THROW(image.isValid(),
                            "loader did not return a valid image for file: "
                            << name);

                        return true;
                }
        }

        // no loader could load image!
        return false;
}



#define ADD_IMAGE_LOADER( reg , type )                                  \
        {                                                               \
                DPRINTF("Adding image loader: '%s'...", #type );        \
                smart_ptr<ImageLoader> loader =                         \
                        create ##type ##ImageLoader();                  \
                ASSERT(loader, "Failed to create loader of type: %s",   \
                    #type );                                            \
                reg->addLoader(loader);                                 \
        }


static Registry *
getRegistry
(
void
)
{
        // lock so that only one thread can get a registry at a time
        //      (avoids having two threads trying to initialize at once)
        static smart_mutex s_mutex;
        mlock l(s_mutex);

        static Registry * s_reg = NULL;
        if (!s_reg) {
                s_reg = new Registry;

                // first time called!  create all the actual image loaders
                // Order of registration matters: the first loader that says
                //      it can load the image will.  I doubt this will ever be
                //      much of an issue since formats are so different...
                ADD_IMAGE_LOADER(s_reg, Png);
                ADD_IMAGE_LOADER(s_reg, Jpeg);

                // A note on thread safety: loadImage() must be callable on
                //      many threads concurrently, which means this registry
                //      must also be threadsafe.
                // At the moment, the registry IS threadsafe because it is
                //      only modified once, during this creation block.
                //      After this, the registry is only read (that is, it
                //      only iterates over registered loaders and never
                //      registers new ones).
                // If the registration model ever changes (for instance,
                //      letting callers add new image loaders on the fly),
                //      then the registry object will need to use a
                //      threadsafe object internally.
        }
        return s_reg;
}



////////////////////////////////////////////////////////////////////////////////
//
//      public API
//
////////////////////////////////////////////////////////////////////////////////

bool
loadImage
(
IN nstream::Manager * mgr,
IN const char * name,
OUT image_t& image
)
{
        perf::Timer timer("loadImage");
        ASSERT(mgr, "null");
        ASSERT(name, "null");

        // posix/linux: need to use our registry of format-specific libraries
        Registry * reg = getRegistry();
        ASSERT(reg, "null");
        return reg->load(mgr, name, image);
}



};      // media namespace